Intermediate Algebra for College Students (7th Edition)

Published by Pearson
ISBN 10: 0-13417-894-7
ISBN 13: 978-0-13417-894-3

Chapter 5 - Section 5.4 - Factoring Trinomials - Exercise Set - Page 363: 130

Answer

$\{-3,0,3\}$

Work Step by Step

We are given the trinomial: $$p(x)=4x^2+bx-1.$$ As the trinomial is a quadratic function, it can be factored if it has real root(s) $$\begin{align*} b^2-4(4)(-1)&\geq 0\\ b^2+16&\geq 0. \end{align*}$$ So the trinomial can be factored for any real value of $b$. $$4x^2+bx-1=(4x+u)(x+v)\text { or } 4x^2+bx-1=(2x+u)(2x+v).$$ $\textbf{Case 1:}$ $4x^2+bx-1=(4x+u)(x+v)$ $$\begin{align*} 4x^2+bx-1&=4x^2+(4v+u)x+uv\\ b&=4v+u\\ uv&=-1\\ u=1,v=-1&\text{ or }u=-1,v=1\\ b=4(-1)+1\text{ or }b=4(1)+(-1)\\ b&=3&\text{ or }b=-3. \end{align*}$$ $\textbf{Case 2:}$ $4x^2+bx-1=(2x+u)(2x+v)$ $$\begin{align*} 4x^2+bx-1&=4x^2+(2u+2v)x+uv\\ b&=2u+2v\\ uv&=-1\\ u=1,v=-1&\text{ or }u=-1,v=1\\ b=2(1)+2(-1)\text{ or }b=2(-1)+2(1)\\ b&=0. \end{align*}$$ So the integer values of $b$ are $\{-3,0,3\}$.
Update this answer!

You can help us out by revising, improving and updating this answer.

Update this answer

After you claim an answer you’ll have 24 hours to send in a draft. An editor will review the submission and either publish your submission or provide feedback.